Bioaccumulation of heavy metals in Liza saliens from the Esmoriz-Paramos coastal lagoon, Portugal

Composition, distribution, and risk assessment of heavy metals in large-scale river water on the Tibetan Plateau

Heavy metals present in aquatic ecosystems constitute a significant threat to both the environment and human health. In this study, we analyzed various heavy metals (As, Cr, Co, Ni, Cu, Mo, Cd, Pb and Sb) using extensive surface water samples collected from the Tibetan Plateau in 2021 and 2023. Results showed that downstream water samples exhibited higher content (mean 12.6 μg/L) of heavy metals compared to those from the glacier basins. It is noteworthy that heavy metal content varied significantly both in the glacier basin and downstream (4.6-29.1 μg/L and 7.8-55.2 μg/L, respectively). However, elevated concentrations at certain sites (e.g., Saga County and Dangque Zangbu River) were primarily attributed to the disproportionate contribution of individual heavy metals, possibly stemming from specific human activities or natural conditions. In the glacier basin, only Cr exhibited a decreasing trend in enrich factors (EF) with increasing Sc concentration, whereas, in the downstream areas, most elements displayed a declining trend. Furthermore, apart from a few sampling sites, heavy metal concentrations in the glacier basin remained relatively balanced, suggesting that these metals predominantly originate from natural sources. The values of potential ecological risk for an individual element (Eri) and potential ecological risk index (PER) indicate that the ecological and human risks associated with almost heavy metals (except As) in the aquatic ecosystem are minimal. ENVIRONMENTAL IMPLICATION: Heavy metals in aquatic ecosystems pose a significant threat to ecological and human health. Due to delicate ecological balance of the Tibetan Plateau and its critical role as a water resource, we analyzed various heavy metals (As, Cr, Co, Ni, Cu, Mo, Cd, Pb and Sb) concentrations and EF in land surface river water, to find out the pollution levels and possible sources of heavy metals in the aquatic ecosystems. The results of risk assessment showed that the prevention and management of arsenic in Tibetan Plateau needs attention, but most heavy metals pose no threaten to ecological and human health.

Antagonistic Effect of Zinc Oxide Nanoparticles Dietary Supplementation Against Chronic Copper Waterborne Exposure on Growth, Behavioral, Biochemical, and Gene Expression Alterations of African Catfish, Clarias gariepinus (Burchell, 1822)

The harmful impact of waterborne copper (Cu) as a common abiotic stressor in aquatic environments has gained much more interest. The present study aimed to investigate the utilization of zinc oxide nanoparticles (ZnONPs) dietary supplementation to mitigate the chronic toxicity of Cu in African catfish (Clarias gariepinus). Two hundred and forty fish (92.94 ± 0.13 g) were assigned into six groups for 60 days. Control (C), ZnONPs20, and ZnONPs30 groups were fed on basal diets fortified with 0, 20, and 30 mg kg-1 ZnONPs without Cu exposure. Cu, Cu + ZnONPs20, and Cu + ZnONPs30 groups were exposed to Cu at a dose of 10 mg L-1 and fed on basal diets fortified with 0, 20, and 30 mg kg-1 ZnONPs, respectively. The results revealed that the Cu-exposed fish experienced abnormal clinical signs and behavioral changes. The growth indices and acetylcholine esterase activity were significantly decreased (P < 0.05) in the Cu group. Meanwhile, hepatorenal and serum stress indices (P < 0.05) were significantly elevated with chronic Cu exposure. In addition, a higher expression of stress (P < 0.05) (heat shock protein 60 and hypoxia-inducible factor-1 alpha) and apoptotic-related genes (C/EBP homologous protein, caspase-3, and Bcl-2 Associated X-protein) with down-regulation (P < 0.05) of the anti-apoptotic-related genes (B-cell lymphoma 2 and proliferating cell nuclear antigen) was noticed in the Cu-exposed fish. Histopathological alterations in the gills, liver, kidney, and spleen were markedly reported in the Cu-exposed group. The dietary supplementation with ZnONPs significantly alleviated the negative impacts of chronic waterborne-Cu exposure on growth performance, physiological changes, gene expression, and tissue architecture, especially at 30 mg kg-1 diet level. In particular, the inclusion of ZnONPs at the 30 mg kg-1 diet level produced better outcomes than the 20 mg kg-1 diet. Overall, ZnONPs could be added as a feed supplement in the C. gariepinus diet to boost the fish's health and productivity and alleviate the stress condition brought on by Cu exposure.

Mitigating marine hazardous contaminants: A sustainable management perspective

Marine hazardous contaminants, such as cadmium (Cd) and lead (Pb), pose significant risks to both human health and aquatic organisms. Traditional methods may not remove contaminants to safe levels, leading to the release of hazardous materials into marine environments. This research proposes polymeric membrane bioreactors as a potential solution to this problem. We determined Cd and Pb levels in three freshwater fish species (Rita, Ompok bimaculatus, and Heteropneustes fossils) from two distinctive regions (Zone 1 and Zone 2). Additionally, Cd and Pb concentrations in feeding materials, water, and sediments were analyzed to estimate daily intake and potential hazardous effects of these contaminants on the fish species. These findings underscore the need for effective regulatory measures and policies to reduce the discharge of hazardous contaminants into freshwater and marine environments, protecting both human health and the environment. Implementing polymeric membrane bioreactors in wastewater treatment and industrial facilities could mitigate the risks associated with consuming contaminated fish species. Significantly, the Cd and Pb levels in all three fish species from both fishponds exceeded the Food and Agriculture Organization's (FAO) maximum permissible limits. These findings carry important implications for policymakers, regulators, and industries, urging them to act appropriately to ensure the safety of the environment and public health. This study suggests that polymeric membrane bioreactors are a promising technological approach to address marine contamination, emphasizing their potential role in safeguarding human health and aquatic ecosystems.

Assessment of Potentially Toxic Metals in Fish from Lake Manyara, Northern Tanzania

Elemental tracer concentrations of copper, lead, nickel and zinc, were assessed in the muscles of Oreochromis amphimelas and Clarias gariepinus from Lake Manyara, Tanzania, to evaluate their safety to consumers, specifically humans. Results revealed that no elemental concentrations exceeded the FAO permissible levels, indicating fish from all sites are safe for human consumption. However, based on the highest found concentration of Pb, we recommend a maximum consumption of 2.2 kg of fish from Lake Manyara per week. No significant differences were observed in the metal concentrations between the two fish species, suggesting there is no bioaccumulation in the food chain. Moreover, no significant differences were found between fish landing sites, indicating there are no regions in the lake with higher pollution. These findings indicate that PTM concentrations have not increased to toxic levels due to increased mobilisation from the catchment. Continued monitoring of potential toxic metal concentrations in fish is recommended due to endorheic nature of Lake Manyara and increasing anthropogenic activities in its catchment area.

Assessment of heavy metal contamination and ecological risk in Morocco's marine and estuarine ecosystems through a combined analysis of surface sediment and bioindicator species: Donax trunculus and Scrobicularia plana

Morocco is one of the most affected regions by heavy metal pollution worldwide. In this study, two ecosystems in Agadir Bay, southern Morocco, were studied seasonally, using surface sediment and bivalve species. The concentrations of Cu, Pb and Cd were determined using the Shimadzu AAS 7000 flame atomic absorption spectrophotometer method. Our results marked average levels corresponding to an unpolluted sediment with a low contamination degree, low ecological risk associated with metal contamination, and levels that did not exceed the thresholds set by EC, USEPA, INERIS and INRH, except for Pb in tourist beach. The principal component analysis findings revealed a positive correlation in the bioaccumulation between the two compartments, with an influence of abiotic parameters. Thus, to better manage environmental pollution in these ecosystems, authorities must implement waste treatment strategies in the surrounding harbor and tourist complexes and prohibit the use of these toxic metals in the coastal areas.

Distribution, Bioaccumulation, and Risks of Pharmaceutical Metabolites and Their Parents: A Case Study in an Yunliang River, Nanjing City

The occurrence, bioaccumulation, and risks of 11 pairs of pharmaceutical metabolites and their respective parents were investigated in the water, sediment, and fish of an urban river in Nanjing city, China. The results showed that most of the target metabolites and their parents were detected in all water samples, with concentrations ranging from 0.1 ng/L to 72.9 ng/L. In some cases, the concentrations of metabolites in water were significantly higher than their parents, with fold changes reaching up 4.1 in the wet season and 6.6 in the dry season, while in sediment and fish, a lower concentration was observed in most cases. A lowered concentration of detected pharmaceuticals was observed in the dry season when compared to the wet season due to the seasonal variation in pharmaceutical consumption and overflow effluent. The bioaccumulation of pharmaceuticals in different fish tissues were detected with a descending order of overall concentration as gill > brain > muscle > gonad > intestine > liver > blood. In addition, the concentrations of both metabolites and their parents also decreased along the river in two seasons. However, the concentration rates of metabolites and their parents were significantly altered along the river in both water and sediment. The relatively high concentration proportions of the detected pharmaceuticals in water suggested that pharmaceuticals were more likely to apportion in water than in sediment, especially for the metabolites. Meanwhile, the rates of the metabolite/parent pairs between fish and water/sediment were generally lower, indicating the higher excretion capacity of metabolites from fish than their parents. Most of the detected pharmaceuticals had no impact on aquatic organisms. However, the presence of ibuprofen posed a medium risk to fish. Compared to the parents, metabolites showed a relatively low risk value but a high contribution to the total risk. It highlights that metabolites in the aquatic environments cannot be ignored.

Bioaccumulation of trace metal elements and biomarker responses in caged juvenile flounder at a polluted site: Effects of fish density and time exposure

This study investigates the effect of fish density and exposure duration on trace metal elements (TME) bioaccumulation and several biomarkers response. Juvenile flounders were caged at low, medium and high densities and exposed during 15 or 30 days in the Seine estuary. The concentrations of the TME measured in the muscle of the caged fish were all in agreement with their bioavailability percentage in the sediments. Higher concentrations of TME were found in flounders' muscle exposed for 15 days compared with those caged for 30 days. For the same exposure time, the density of fish had no effect on the accumulation of the TME in the flounders' muscle. Biomarkers responses varied according to density and duration of exposure. Special care should be taken in their interpretation. We underline that for an optimal assessment of TME pollution in the field, 15 days with low densities of fish per cage are sufficient.

Concentrations, bioaccumulation, and health risk assessments of heavy metals in fishes from Nigeria's freshwater: a general overview

Heavy metals (HMs) have attracted global attention due to their toxicity, persistence, and accumulation in aquatic fish in the polluted water environment. The consumption of these fishes exposed humans to a higher risk of non-carcinogenic and carcinogenic risks. In this study, we provided a critical overview of the potential sources and concentration of HMs in Nigeria's freshwater. Furthermore, we reported their pollution level in widely eaten fish species in the country. Our findings show that effluent from anthropogenic and industrial activities is one of the major sources HMs in the country. The mean concentration of Zn (9.02 mg/L), As (7.25 mg/L), Cu (4.35 mg/L), Fe (1.77 mg/L), and Pb (1.46 mg/L) in Nigeria's freshwaters were found to be high than Nigerian Standard for Drinking Water Quality permissible limit. This study demonstrated considerable health risks associated HMs via dietary consumption of different fishes from polluted waters. Therefore, we recommended an urgent need for effective management HMs in water bodies in order to protect the lives of people living in the country.

Bioaccumulation, Detoxification, and Biological Macromolecular Damage of Benzo[a]pyrene in Exposure in Tissues and Subcellular Fractions of Scallop Chlamys farreri

Because of the persistence and high toxicity of benzo[a]pyrene (B[a]P), the bioaccumulation and detoxification mechanisms of B[a]P have been studied extensively at the tissue level; but the data at the subcellular level in bivalves have not been reported. The present study was conducted to investigate the effects of B[a]P exposure on bioaccumulation, detoxification, and biomacromolecular damage in gills, digestive glands, and their subcellular fractions of the scallop Chlamys farreri. The subcellular fraction contains cytoplasm, mitochondria, microsome, nucleus, cell membrane, and overall organelle. The results demonstrated that B[a]P accumulation showed a clear time-dose effect. Based on the time-dependent accumulation of B[a]P in subcellular fractions, we speculated that the intracellular migration order of B[a]P was cell membrane, organelle, and nucleus in turn. Considering the difference of B[a]P accumulation may be related to B[a]P metabolism, we have further confirmed that the activities of B[a]P metabolizing enzymes in scallop tissues and subcellular fractions were significantly tempted by B[a]P (p < 0.05), including 7-ethoxyresorufin O-deethylase (increased), glutathione-S-transferase (GST; decreased), and superoxide dismutase (increased). First, GST was detected in bivalve cytoplasm and microsome. Second, B[a]P exposure also caused biomacromolecules damage. The results demonstrated that mitochondria and microsome were more vulnerable to lipid peroxidation than cell membrane and nucleus. Taken together, the present study fills some of the gaps in our knowledge of the bioaccumulation and detoxification mechanisms of C. farreri exposed to B[a]P in subcellular fractions and deeply explores the transportation and the main metabolic and damage sites of polycyclic aromatic hydrocarbons (PAHs) in cells, which helped us to comprehensively understand the toxic mechanism of PAHs on bivalves. Environ Toxicol Chem 2022;41:2353-2364. © 2022 SETAC.

Impact of nickel mining in New Caledonia on marbled eels Anguilla marmorata

New Caledonia is particularly affected by nickel open pit mining activities because of the presence of ultramafic soils rich in metals. The particles dispersed by atmospheric transport and soil erosion during the excavation of nickel end up by deposition or leaching in rivers where they may be bioaccumulated by organisms living downstream the mines. Despite alarming freshwater metals concentrations, no study investigated the level of their bioaccumulation in eels, and if high bioaccumulation levels occur, the potential consequences on their health. The aim of this study was to determine how eels Anguilla marmorata are impacted in situ by metals issued from mining activity by measuring: morphometric parameters; metal concentrations in tissues and organs and transcription levels of target genes encoding proteins involved in several metabolic key functions. Among organs, liver was found to be the most affected by mining with average nickel concentrations of 5.14 mg/kg versus 1.63 mg/kg for eels away from mines leading to dysregulation of numerous genes involved in oxidative stress, DNA repair, apoptosis, reproduction and both lipid and mitochondrial metabolisms. This study should allow us to define in an integrated way if metals released by mining activities influence metals bioaccumulation in eels and induce biological effects.

Toxic metals and total lipids comparison between wild and farmed fish of South mediterranean

A total of 151 wild and farmed fish samples of three species (S. aurata, D. labrax and U. cirrosa) from south Mediterranean were examined for cadmium, lead and mercury and total lipids detection to verify possible differences between wild and farmed fish. Mercury was detected only in S. aurata samples, with mean values of 0.056 ± 0.128 mg/kg and 0.031 ± 0.033 mg/kg for farmed and wild samples, respectively. The results verified no significant differences in Pb, Cd and Hg levels between wild and farmed fish samples (p < 0.05). The farmed fish samples showed higher total lipids contents than wild (p > 0.05). As far as we know, this work report first findings on the toxic metal presence in farmed Umbrina cirrosa, showing no detectable Hg, Cd and Pb values. The results of this work seems to confirm that the presence of toxic metals could be more related to the pollution the site than the type of production.

Trace element assessment in Neoechinorhynchus agilis (Rudolphi, 1918) (Acanthocephala: Neoechinorhynchidae) and its fish hosts, Mugil cephalus (Linnaeus, 1758) and Chelon ramada (Risso, 1827) from Ichkeul Lagoon, Tunisia

Acanthocephalans belonging to the species Neoechinorhynchus agilis were collected from two mullets, Mugil cephalus and Chelon ramada from Ichkeul Lagoon in northern Tunisia. Collected parasites, as well as tissues of their hosts (muscle, liver and intestine), were analysed for trace elements (silver, arsenic, cadmium, cobalt, copper, iron, manganese, nickel (Ni), lead (Pb), selenium, vanadium (V), zinc) using inductively coupled plasma mass spectrometry. Our results showed different accumulation patterns of trace elements in fish tissues and parasites. Among the host tissues, liver accumulated the highest metal amounts. Acanthocephalans showed Ni, Pb and V in significantly higher concentrations compared to their host's tissues. Further, the calculated bioconcentration factors demonstrated a 390-fold higher Pb accumulation in the parasite compared to fish muscle. This study is the first field survey in Tunisia dealing with elements' uptake in parasites and their hosts. Our results corroborate the usefulness of the acanthocephalans for biomonitoring of metal pollution in aquatic ecosystems and promote more research in order to understand host-parasite systems in brackish waters of the Mediterranean area.

An assessment of level of heavy metals pollution in the water, sediment and aquatic organisms: A perspective of tackling environmental threats for food security

Pollution is severely threatening the wetland habitats. Heavy metals are one among of the major pollutants in wetland habitats. The cadmium (Cd), copper (Cu), chromium (Cr), cobalt (Co), lead (Pb), mercury (Hg), nickel (Ni) and zinc (Zn), were assessed in the water, sediment, benthic species (polychaetes, mollusc and crustaceans), prawn and fishes. The assessment of heavy metals was done by using double-beam Atomic Absorption Spectrophotometer (AAS). The Hg, Cr and Co were greater in sediment, Ni and Cd were higher in polychaetes and molluscs respectively. However, the Cu and Pb greater in crabs and the Zinc was greater in fishes. The concentration of metals showed significant differences among the various sources examined (P < 0.05) except Cr (P > 0.05). The inter-correlational analysis among the metals assessed from the various sources showed that the Cr and Pb not correlated among the eight metals examined. However, the Cu and Co were correlated with Hg (r = 0.307) and (r = 0.788) respectively. The nickel was correlated with Hg (r = 0.367), Cu (r = 0.362) and Co (r = 0.432). The Zinc was correlated with the Cd (r = 0.331) and Hg (r = 0.737). However, correlation of metals among the different sources shown that the metals of polychaetes correlated with sediment r = 0.637, the metals of crabs correlated with the sediment and polychaetes r = 0.630 and r = 842 respectively, the metals of molluscs was also correlated with sediment (r = 0.636), polychaetes (r = 0.889) and crabs (r = 0.894). In addition to that the metals of prawns was correlated with the polychaetes (r = 839), crabs (r = 0.628) and molluscs (r = 0.634). The metals of fishes correlated with polychaetes (r = 0.529), crabs (r = 0.710), molluscs (r = 0.493) and prawns (r = 0.593). Indeed the multiple regression model explained that the metals of sediments influence the accumulation of metals in biotic species such as polychaetes, molluscs, crustaceans, prawns and fishes with 84% (F = 21.079; p < 0.001).The order of the heavy metals in the water, sediment and biotic species was Hg > Pb > Ni > Cr > Zn > Co > Cu > Cd. The study found that the level of heavy metals at various sources in the sanctuary is showing considerable warning and the sanctuary is required intensive assessment on various aspects of pollution since the Point Calimere Wildlife Sanctuary is supporting several species of migratory and endangered shorebirds seasonally.

A seasonal comparison of trace metal concentrations in the tissues of Arctic charr (Salvelinus alpinus) in Northern Québec, Canada

Ecotoxicological research detailing trace metal contamination and seasonal variation in the tissues of northern fishes such as Arctic charr (Salvelinus alpinus) has been poorly represented in the literature beyond examination of mercury. In an effort to address this, anadromous Arctic charr were collected from the Deception River watershed in the late summer and post-winter season, before quantifying seasonal and organotropic variations in dorsal muscle and liver concentrations of arsenic, cadmium, chromium, copper, nickel, lead, and zinc. Potential linkages with biological variables (fork length, age, and somatic condition) and indicators of feeding behavior (δ¹³C and δ¹⁵N) were also assessed. Trace metal organotropism favouring elevation in liver tissue concentrations was exhibited by cadmium, copper, nickel and zinc, while arsenic, chromium and lead exhibited no significant organotropic variation. Seasonal differences in concentrations were metal and tissue dependent, but generally increased in tissues collected from post-winter sampled Arctic charr. Significant correlations with biological and trophic descriptors were also determined to be element and tissue dependent. These parameters, in addition to season, were incorporated into multi-predictor variable models, where variations in trace metal concentration data were often best explained when season, somatic condition, and trophic descriptors were included. These variables were also of greatest relative importance across all considered trace metals and tissue types. These findings suggest that seasonally linked processes have the greatest influence on trace metal concentrations in anadromous Arctic charr. Future metal-related research on Arctic charr and other northern fish species should further consider these variables when evaluating elemental accumulation.

Diversity in Micromineral Distribution Within the Body of Ornamental Fish Species

This study was conducted to compare micromineral homeostasis across ornamental fish species. Ten different species (n = 3, total = 30) of live ornamental fish were randomly sampled from one big aquarium in a pet store in Belgium. All fish samples were dissected manually for the collection of targeted tissues. The tissue samples were ashed by microwave oven, and the extract was analyzed for copper (Cu), iron (Fe), and Zinc (Zn) by inductively coupled plasma mass spectrometry. Fe was associated with Cu in muscle tissue (p < 0.05), but neither of them were associated with Zn in the muscle. However, the three micromineral concentrations were correlated in the heart (p < 0.05). Similarly, all of them were correlated in the liver (p < 0.05), but none of them showed a significant association in the tail fin. Excess deposition of minerals in heart tissue is a new observation, and it is not known if this is meant as storage or rather the fish heart has a high requirement for microminerals. Storage in the tail fin should be interpreted as a sign of permanent deposition as a tool to dispose off toxic excess. The lack of correlation between the muscular concentrations of Zn on the one hand, and those of Fe and Cu on the other hand, further suggests that fish species distinctly differ in their micromineral metabolism. Although this exploratory study still leaves many questions unanswered, it points to the large diversity in micromineral metabolism among fish species.

Rice intercropping with alligator flag (Thalia dealbata): A novel model to produce safe cereal grains while remediating cadmium contaminated paddy soil

Phytoremediation has been employed as a cost-effective technique to remove the cadmium (Cd) from soil and water in several ecosystems. However, little is known about whether intercropping the remediating plants with rice (Oryza sativa) crop could reduce Cd accumulation in rice grains. We conducted greenhouse pot and concrete pond trials to explore the effects of intercropping alligator flag (Thalia dealbata, Marantaceae) on soil Cd remediation, paddy soil and microbial properties, and rice production. Our results suggest that intercropping with alligator flag significantly decreased Cd absorption, transportation, and accumulation from the soil to the rice grains (under 0.2 mg kg^-1 at a soil Cd content below 2.50 mg kg^-1). This decrease was due to the lowered Cd availability and higher soil pH in the rice-alligator flag intercropping system. Although planting alligator flag resulted in the reduction of soil NH₄-N and NO₃-N, Cd content in the rhizosphere was the main factor restricting microbial biomass, species, and community composition. Alligator flag could tolerate higher Cd contamination, and accumulate and stabilize more Cd in its tissues than rice. Our study suggests that alligator flag intercropped with rice has potential as a phytostabilization plant to produce rice safely for human consumption in moderately Cd-contaminated soils.

Investigation of toxic elements in Carassius gibelio and Sinanodonta woodiana and its health risk to humans

Increasing toxic metal content in aquatic products has become a universal burden due to the risks to aquatic organisms and human health associated with the consumption of these products. In this study, toxic metal distribution and accumulation in the organs of fish and bivalve species of economic and culinary importance from the lower reaches of the Yangtze River are examined, and the corresponding health risks are also investigated. In general, the viscera and gill show higher concentration of metals than other tissues. The order of the accumulation sequence of metals in muscle tissue of fish and bivalve is Zn > Cu > Mn > Cr > As > Hg > Pb > Cd and Mn > Zn > Cu > As > Cr > Pb > Cd > Hg respectively. Maximum accumulation of Mn (507.50 μg g^-1) and Pb (0.51 μg g^-1) in the gill tissues indicates the major uptake of these metals from the water column. According to the Hazard Index (HI) calculations (based on USEPA), the analyzed metals will not cause any harmful health effects to individuals for both normal and habitual fish consumers, except for Hg and As in habitual consumers, if these species are consumed at a larger amount. Compared to the Chinese Food Health Criterion and other international standards (WHO/FAO), metal concentrations in the edible muscle tissues of the studied species are lesser than the acceptable levels and found to be fit for human consumption.

Sources of Potentially Toxic Elements in Sediments of the Mussulo Lagoon (Angola) and Implications for Human Health

The Mussulo lagoon is a coastal environment located near Luanda, one of the SW African cities that has been growing more rapidly during the last decades. Geochemical, mineralogical, and grain-size data obtained for the lagoon sediments are analyzed together, in order to establish the factors that control the distribution of some potentially toxic elements (PTEs). Sediments from northern location tend to be enriched in feldspar and, despite some variability in grain-size distributions, in fine-grained detrital minerals; southern lagoon sediments display very homogenous grain-size distribution and are enriched in minerals associated with salt precipitation (halite and gypsum). Multivariate statistics reveal a close link between some PTEs, namely Co, Hg, Ni, and Pb, for which an anthropogenic source can be postulated. On the other end, As seems to be associated with natural authigenic precipitation in southern lagoon sectors. Sediments enriched in clay also tend to yield more Fe, Mn, Zn, and Cu, but it is unclear whether their sources are natural or anthropogenic. Hazard indexes calculated for children are higher than 1 for As and Co, indicating potential non-carcinogenic risk. For the other elements, and for adults, there is no potential carcinogenic or non-carcinogenic risk.

Naturally selected dominant weeds as heavy metal accumulators and excluders assisted by rhizosphere bacteria in a mining area

Managers need more practical and promising plants for use in heavy metal phytoremediation. Although previous studies have identified the potential of some weeds and microbial strains in phytoremediation, the potential of dominant weeds and the relationship between weeds and their rhizosphere bacterial strains are still unknown. In our study, we examined dominant weeds in the Dabaoshan mine located in Guangdong province, China to test their abilities as heavy metal accumulators and excluders. Results suggest that Ludwigia prostrata exhibited the highest potential for accumulating Cu, Pb and Zn compared with the other plants. Specifically, L. prostrata accumulated 71.58, 130.76 and 454.72 mg kg^-1 of Cu, Pb and Zn, respectively; the species' translocation factor of Zn was 2.04, indicating a high accumulation of Zn. In contrast, the Cd translocation factor (TF) of Digitaria sanguinalis was 0.18, significantly lower than that of other plant species examined. Our results suggest that Ludwigia prostrata hyperaccumulates Zn and may also serve as a potential candidate remediation plant for Cu and Pb due to its high absolute accumulation amount of Cu and Pb, while Digitaria sanguinalis may be a potential candidate as a Cd excluder. We also found that rhizosphere bacterial communities were shaped by individual dominant plant species. Chloroflexi was the most dominant phylum in accumulator plant such as Fimbristylis miliacea, while Cyanobacteria was the most dominant phylum in excluder plant such as Digitaria sanguinalis. Our study provides insights for selecting new weedy forbs and grasses, rhizosphere bacterial species and developing approaches for phytoremediation and phytostabilization.

Biomonitoring of Heavy Metals in River Ganga Water, Sediments, Plant, and Fishes of Different Trophic Levels

In this study, the pattern of metals concentration in water, sediment, plants, and three edible fish species (Channa striata, Labeo rohita, and Catla catla) of different trophic levels, captured from Jajmau (Kanpur), an important fishery area of river Ganga in Uttar Pradesh, India was examined. The heavy metals, Ni, Pb, Fe, Cu, Zn, Cd, Cr, and Co, were estimated in the liver, kidney, muscles, and gill tissues of abovesaid species of fish. The highest metal concentration was reported in the bottom feeder fish as compared with the column and surface feeders. The result obtained after analysis of water sample reflects the order of occurrence of heavy metals as Fe > Cr > Pb > Ni > Cd > Zn > Cu > Co. Sediments analysis indicates high concentration of Fe and Cr, making the entire environment from top to bottom, stressful. Target hazard quotient (THQ) and hazard index (HI) of the three species suggest a potential risk to the health of consumers, the humans. Thus, it is inevitable that the river Ganga should be closely monitored to safeguard human health. Graphical Abstract.

Concerns and Threats of Contamination on Aquatic Ecosystems

Aquatic ecosystems are the ultimate sinks for the contaminants. Water contamination is the outcome of human activities such as urbanization, industrialization, and agricultural activities. The overuse of pesticides and fertilizers and sewage from residential and industrial areas ultimately find its way to aquatic environment. Thus results in the degradation of the water quality and leads to the spread of infectious diseases such as dysentery, diarrhea, and jaundice. Contamination in aquatic environs is one of the leading types of pollution which has significant negative health issues and mortality. Water has a natural capacity to neutralize the contamination, but when contamination becomes uncontrolled, water will lose its self-generating capacity. Therefore, there is a need for regular monitoring and controlling of pollutant discharge into the nearby aquatic environs.

Metabolomics Provide Sensitive Insights into the Impacts of Low Level Environmental Contamination on Fish Health-A Pilot Study

This exploratory study aims to investigate the health of sand flathead (Platycephalus bassensis) sampled from five sites in Port Phillip Bay, Australia using gas chromatography-mass spectrometry (GC-MS) metabolomics approaches. Three of the sites were the recipients of industrial, agricultural, and urban run-off and were considered urban sites, while the remaining two sites were remote from contaminant inputs, and hence classed as rural sites. Morphological parameters as well as polar and free fatty acid metabolites were used to investigate inter-site differences in fish health. Significant differences in liver somatic index (LSI) and metabolite abundance were observed between the urban and rural sites. Differences included higher LSI, an increased abundance of amino acids and energy metabolites, and reduced abundance of free fatty acids at the urban sites compared to the rural sites. These differences might be related to the additional energy requirements needed to cope with low-level contaminant exposure through energy demanding processes such as detoxification and antioxidant responses as well as differences in diet between the sites. In this study, we demonstrate that metabolomics approaches can offer a greater level of sensitivity compared to traditional parameters such as physiological parameters or biochemical markers of fish health, most of which showed no or little inter-site differences in the present study. Moreover, the metabolite responses are more informative than traditional biomarkers in terms of biological significance as disturbances in specific metabolic pathways can be identified.

Trace element contamination in fish impacted by bauxite red mud disposal in the Cassidaigne canyon (NW French Mediterranean)

From 1966 to 2015, the Gardanne alumina refinery discharged some 20 million tons of bauxite residue (called red mud) into the Cassidaigne Canyon (northwest French Mediterranean) with impacts on local ecosystem functioning. Although these red muds contained high levels of trace elements (TE), in particular titanium (Ti), vanadium (V), aluminum (Al) and arsenic (As), surprisingly, their impacts on fish contamination levels and the risk related to fish consumption have been little studied until now. Here, 11 trace elements (Al, As, Cd, Cr, Co, Cr, Mn, Ni, Pb, Ti and V) were analyzed in muscle and, when possible, liver, from 1308 fish of 26 species from an impacted zone in the vicinity of the Cassidaigne Canyon and a reference zone, unaffected by red mud disposals. Moreover, 66 arsenic speciation analyses were performed. Although the impact of human activities on the levels of fish contamination by trace elements is generally not easy to assess in situ because it is blurred by interaction with biological effects, we highlighted significant contamination of the fish species collected from the Cassidaigne Canyon, especially by the main trace elements attributable to the discharges of the Gardanne alumina refinery, namely Al, V and Ti. Moreover, inorganic toxic As concentrations were higher in the impacted zone. The results of this baseline research also confirmed the concern previously raised regarding Hg in Mediterranean organisms and that trace element contamination levels in fish are generally negatively related to fish length for all TE except Hg.

Cadmium and Lead Hazardous Impact Assessment of Pond Fish Species

The current study aims to assess the concentration of cadmium (Cd) and lead (Pb) in five tissues of Cirrhinus mrigala, Labeo rohita, and Catla catla collected from fishponds of Jamshoro and Larkana, Sindh, Pakistan. Meanwhile, the levels of Cd and Pb in feeding materials, water, and sediments of fishponds of both areas were also studied. The daily intake and hazardous impact assessment of Cd and Pb by muscles of three fish species of fishponds of both areas were estimated. The concentration of Cd in tissues of C. mrigala and C. catla of Larkana were higher than that in tissues of same fish species of Jamshoro whilst Pb contents in tissues of fishes of Jamshoro were high (p > 0.05). The feeding materials of fishponds of Larkana were enriched with Cd whilst Pb was high in feeding material of fishponds of Jamshoro. The estimated bioaccumulation factor, average daily intake, and hazardous quotient of Pb were high as compared to Cd in all studied fish species of fishponds of Larkana and Jamshoro. The hazardous quotient of Pb indicated that the local population of both areas might have a potential toxic risk. Graphical abstract ᅟ.

Trace metals in striped dolphins (Stenella coeruleoalba) stranded along the Murcia coastline, Mediterranean Sea, during the period 2009-2015

Mercury (Hg), cadmium (Cd), lead (Pb), selenium (Se) and arsenic (As) concentrations in internal tissues of 72 striped dolphins (Stenella coeruleoalba) from Murcia Region (Mediterranean coastline) have been investigated for the first time. Hg showed the highest concentration, followed by Se, Cd, As and Pb. In general, the levels of metal found in this study were similar to those described in similar studies in the Mediterranean Sea. However, in some adult specimens, Hg liver concentrations were related with toxic effects in cetacean. A significant correlation was observed with age, likewise between Se and Hg and Cd in tissues, which agree with detoxify effect attributed to Se through inert complex formation. Molar ratio Hg:Se in liver was close to 1:1 in some specimens, which would indicate overload of the Hg-Se detoxify function and compromised health. These results could contribute to a better knowledge of the distribution of these persistent pollutants in the Mediterranean Sea.

Mass mortality of fish and water quality assessment in the tropical Adyar estuary, South India

Mass mortality of fishes was reported at the Adyar estuary, South India, during November 2017. The probable reasons for fish mortality are analyzed in this paper. Critical assessments on water quality parameters including the metal concentrations, nutrients, and histology of gills and liver of fish (Mugil cephalus) isolated from the impact zone were performed. Among the metals observed, chromium showed levels (3.64 ± 0.001 mg L^-1) much above the average permissible limits (0.1 mg L^-1). The measured values of physico-chemical parameters in the impact zone are as follows: dissolved oxygen 4.7 ± 0.22 mg L^-1, total alkalinity 132 ± 4 CaCO₃ mg L^-1, salinity 5.3 ± 0.3 PSU, temperature 27.8 ± 0.16 °C, nitrate, 1.66 ± 0.48 mg L^-1, nitrite 0.01 ± 0.0008 mg L^-1, ammonia 0.03 ± 0.001 mg L^-1, phosphate 1.52 ± 0.002 mg L^-1, and silicate 13.85 ± 3.1 mg L^-1. The low salinity could have escalated the toxicity of the metal. In addition, histology of gills and liver showed cellular necrosis, epithelial lifting, hyperplasia, edema, mucous cell proliferation in the gills, cytoplasmic vacuolation of hepatocytes, and degeneration of liver which reveal that chromium toxicity is the most probable cause for mass mortality.

Evaluation of Nutritional and Mineral-Heavy Metal Contents of Horse Mackerel (Trachurus trachurus) in the Middle Black Sea in terms of Human Health

In this study, the effects of seasonal and sexual differences on the nutritional composition, macro (Na, Mg, P, K, Ca), trace element (Mn, Fe, Co, Cu, Zn, Mo, Ni, Se) and potential toxic metal levels (Cd, Pb, As) of horse mackerel (Trachurus trachurus) caught in the middle Black Sea coast during all seasons were investigated. The metal levels of muscle tissues of the examined specimens were determined using ICP-MS instrument. The results showed that horse mackerel had a high nutritional value in terms of protein and lipid levels. Metal levels were found to be different in terms of sexual and seasonal factors. With regard to macro element levels, horse mackerel muscle was found to be rich. Zn and Cu levels of the trace elements were below the legal limits specified by the codex. It was also observed that the levels of Cd and Pb in horse mackerel muscle tissue were below the FAO (Food Agriculture Organ U N 464:5-10, 1983) limit values and above the TFC (Turkish Food Codex 2011) limit values. In terms of EWI and EDI values, horse mackerel was found to be non-toxic. This study suggests that horse mackerel is beneficial seafood for human health and nutrition.

Impact of mining on metal concentration in waters of the Zuari estuary, India

The rationale of the current study was to establish that mining and associated activities are the chief sources of trace metal contamination in the Zuari estuary, Goa. Surface and bottom water samples were collected monthly, at 11 stations, starting from the mouth of the estuary, covering a stretch of 35 km towards the head during the period of ban on mining in Goa as per the directions of the Honourable Supreme Court of India. The water samples were analysed for physicochemical parameters and metals (Fe, Mn, Zn, Cr, Cu and Pb). Spatial variation of metals (Zn, Cr and Cu) indicated high concentrations at the mouth region, revealing that they are derived by resuspension of bottom sediments at higher salinities, while metals Fe, Mn and Pb showed higher concentrations at the head region, indicating that these are derived from freshwater discharge. Seasonal variation of metals revealing high concentrations during non-monsoonal months was attributed to a high rate of evaporation and intense anthropogenic activities except Pb. Contamination factors and enrichment factors of metals were calculated to assess the degree of metal contamination and relative abundance of pollutants, respectively. Sources of metals into the estuary were discussed by using principal component analysis. Correlation coefficients were calculated to find out the dynamics among the physicochemical factors and trace metals. The study exemplified that concentrations of trace metals in waters of the Zuari estuary were significantly less when compared to the periods of rampant mining activity around Goa, indicating that mining can influence the concentration of metals in the Zuari estuary.

Baseline evaluation of metal contamination in teleost fishes of the Gulf of Tigullio (north-western Italy): Histopathology and chemical analysis

Metals, whether essential (Cu, Zn, Cr, Fe, Mn) or non-essential (Al, As, Cd, Ni, Pb, Hg) for organism metabolism, occur naturally in the marine environment and their abundance can increase due to the presence of human activities. In this study, fish were used as bio-indicators, to determine a correlation between the bio-accumulation of metals in muscle and gill tissues and the health status of fish. The study area was the Gulf of Tigullio (north-western Italy), which is impacted by various sources of metal contamination. Histopathology served as a significant tool to investigate possible alterations in gills, one of the main organs involved in fish physiology. Results highlighted some correlations between certain metals (e.g. Pb, Ni) and gill alterations (e.g. epithelial hyperplasia, epithelial lifting), providing baseline data from a pool of different fish species, which can be used for comparison purposes in further studies.

Heavy metal contamination in two commercial fish species of a trans-Himalayan freshwater ecosystem

Toxic metals have disturbed the quality of freshwater ecosystems worldwide. The concentration of heavy metals was investigated in liver, gills and muscle tissues of Schizothorax niger and Cyprinus carpio captured from river Jhelum of Kashmir Himalaya. The heavy metals displayed a wide range of disparity in studied tissues, seasons, sites and species. Cu²⁺ exhibited the highest concentration (279.6 μg/kg) in the liver tissues of S. niger in autumn at site 2 and the lowest (53.1 μg/kg) in the gill tissues in winter at site 1. In C. carpio, the Cu²⁺ was recorded highest (309.4 μg/kg) in the liver tissues in autumn at site 2. The concentration of Zn²⁺ was found highest (575.7 μg/kg) in the liver tissues at site 2 and the lowest (65.8 μg/kg) was recorded in the muscle tissues in autumn at site 1. Zn²⁺ was recorded highest (416.6 μg/kg) in the liver tissues in autumn at site 3 and lowest (51.5 μg/kg) in the gills of C. carpio during winter at site 1 (control). The concentration of Pb²⁺ (14.42 μg/kg) and Fe²⁺ (323.9 μg/kg) was observed in the liver tissue and gills of S. niger at site 3. Similar levels of Pb²⁺ and Fe²⁺ were recorded in the tissues of C. carpio at different sites. Four-way ANOVA (four way) indicated a statistically significant variation (p ≤ 0.05) in heavy metals with the sites, seasons, species and organs. The study emphasises the utmost need to monitor the level of heavy metals in S. niger on a regular basis as this native fish species is showing a continuous decline in the freshwater ecosystems of Kashmir Valley.

Trace elements and microbiological parameters in farmed Nile tilapia with emphasis on muscle, water, sediment and feed

Fish may bioaccumulate contaminants from the aquatic environment and extend them to the food chain provoking risks to human health. This study evaluated the microbiological parameters of the pond´s water and trace elements concentrations in samples of water, sediment, feed and muscle of farmed Nile tilapia used for human consumption in southern Brazil. A total of 240 fish were collected from 12 tilapia farms. Sediment, tank water and dry ration used in the animals' diet were collected for analysis. Analysis were performed by Energy Dispersion X-ray Fluorescence (EDXRF), Inductively Coupled Plasma Mass Spectrometer (ICP-MS), Induced Coupled Plasma Optical Emission Spectrometer (ICP-OES), and Atomic Absorption Spectrometer (AAS-VGA). In addition, the microbiological analysis of the water was carried out. The concentrations of Se, I, Fe, Cu and Zn in fish muscle were higher than the recommended by the Brazilian legislation, considering the advised daily intake for adults. The arsenic element had concentrations above the limit stipulated by the present Brazilian legislation, observed in all samples of muscle, sediment and tank water highlighting a possible environmental and fish contamination by the toxic element. Moreover, the arsenic concentration in the water presented a positive correlation (ρ = 0.33) with arsenic in the muscle, suggesting that tilapia is a good environmental bioindicator, once they properly reflect the levels of arsenic in the water. It is suggested to perform an arsenic speciation for quantification of the inorganic form and accurate assessment of the degree of toxicity in the muscle samples and risks it can bring to human health. Regarding the other potentially toxic elements (Hg, Pb and Cd), and microbiological analysis of water it was verified that the consumption of the fish in question does not raise risks, since the values are within a quality benchmark established by law. The concentration of total and fecal coliforms in pond´s water in the facilities was in agreement with the microbiological indexes required by the legislation of CONAMA class II. Western region presented the lowest concentrations of fecal coliforms when compared to the other regions. There was no significant difference in the microbiological counts of total heterotrophic bacteria, Vibrio spp. and Pseudomonas spp. among the regions.

Safety assessment on microbial and heavy metal concentration in Clarias gariepinus (African catfish) cultured in treated wastewater pond in Kumasi, Ghana

This study assesses the microbial and heavy metal distribution in African catfish (Clarias gariepinus) cultured in waste stabilization pond, and their subsequent suitability for human consumption. Treated wastewater-fed pond (WFP) was used in the culture of the fish with a non-wastewater fed pond (NWFP), fed with ground and rain water as control. Pond water, sediments and fish tissue (gill, liver, gut and skin) samples from both sources were analyzed for pathogens and heavy metal levels. Escherichia coli populations in the sediments and water from the WFP exceeded the maximum permissible limit by 2-3 log units as expected. Significantly higher levels of pathogen contamination were detected in the gut and skin of fish from the WFP than the NWFP. Heavy metal concentrations in all samples fell within the Food and Agricultural Organization (FAO)/World Health Organization (WHO) and National Oceanic and Atmospheric Administration (NOAA) permissible limits except for iron and cadmium. There were significantly higher heavy metal concentrations in gill and liver than the muscle. Even though iron recorded the highest concentrations in fish tissue, the concentrations (0.1-2.0 mg kg^-1) were below the expected daily nutritional requirement (1-2 mg) for humans and pose no toxicological risk. However, catfish from WFP would require precautionary measures such as cooking/grilling prior to consumption to avoid pathogen infection.

Potential health risk consequences of heavy metal concentrations in surface water, shrimp (Macrobrachium macrobrachion) and fish (Brycinus longipinnis) from Benin River, Nigeria

Health risk consequences of consumption of heavy metal-contaminated water, shrimp (Macrobrachium macrobrachion) and fish (Brycinus longipinnis) from Benin River in Nigeria were evaluated. Three stations around Koko Community (Abialegbe, Ebenco/Optima and Total Facility) with known anthropogenic activities (industrial and petrochemical installations and loading) were studied. Samples of surface water, shrimp and fish were collected and analyzed using Buck scientific atomic absorption spectrophotometer, model 210VGP. Health risk indices were reported as Estimated Daily Intake (EDI), Target Hazard Quotient (THQ) and Total Target Hazard Quotient (TTHQ). Eight heavy metals were analyzed in water, shrimp and fish. Nickel (Ni) was observed to be the most dominant heavy metal in water, while Iron (Fe) was the most dominant in shrimp and fish. Heavy metal levels in water were below recommended limits set by World Health Organization (WHO) and Standard Organization of Nigeria (SON) except for cadmium (Cd), nickel (Ni) and lead (Pb). Assessment of non-carcinogenic health risk by target hazard quotient (THQ) indicated that THQ estimated for heavy metals in water (dermal exposure) and shrimp were below the threshold value of 1. However, THQ for heavy metals in water (oral exposure) and consumption of fish were above threshold value of 1 indicating potential health risk. Total Target Hazard Quotient (TTHQ) estimated for heavy metals in water (oral exposure) and consumption of fish were above 1 indicating potential non-carcinogenic health risk to consumers. The continuous monitoring of heavy metals in Benin River is of necessity in order to ensure the safety of aquatic organisms and humans who rely heavily on aquatic resources.

Physico-chemical forms of copper in water and sediments of Lake Pontchartrain basin, USA

In this study, one of the largest estuaries in the Gulf Coast of USA was investigated for Cu forms and fractionations. Both the water and sediment samples in subsegments of the Lake Pontchartrain basin were collected and Cu forms in dissolved phase and sediment phase were analyzed. The BCR sequential extraction procedure was used to extract Cu in exchangeable, reducible, oxidizable and residual fractions in sediments. The results showed that the residual fraction of Cu was a major contributor in Tangipahoa River and I-10 Bridge sediments, while the residual and oxidizable fractions in the case of oil refinery sediments. Cu partitioning in Lake Pontchartrain basin water showed the decreasing trend of inert > labile > organic in both spring and summer. The release of Cu from the sediments into the water column was greater in summer as compared to spring and vice versa. Lower temperature helps in the adsorption of Cu on the surface of sediments in early spring due to low disturbance and temperature.

Effects of dissolved organic matter, feeding, and water flow on the bioconcentration of diclofenac in crucian carp (Carassius auratus)

Diclofenac (DCF), a prevalent anti-inflammatory drug, is frequently detected in aquatic organisms. However, little is known about the environmental factors that affect the bioconcentration of DCF in aquatic environments. Here, we firstly investigated the bioconcentration of DCF by crucian carp (Carassius auratus) following aqueous exposure (3.57, 14.5, and 71.8 μg L^-1) for 21 days. DCF can accumulate in crucian carp, and the maximum bioconcentration factors (BCFs) of 121 L kg^-1 in the liver, 52.3 L kg^-1 in the gills, and 46.8 L kg^-1 in the muscle were always found at 3.57 μg L^-1 after 14 days of exposure. Secondly, the influences of dissolved organic matter (DOM), feeding, and water flow on the bioconcentration of DCF were determined at the nominal concentration of 4 μg L^-1 for 14 days. The BCFs of DCF in various fish tissues decreased by 0.5-85% with the increasing DOM concentrations. Feeding also led to lower body burden of DCF in fish tissues (6-55%) with the increasing food amount. In hydrodynamic experiment, the BCFs of DCF decreased by15-57% at most in various fish tissues. Collectively, our results demonstrated the bioconcentration of DCF in fish can be influenced by various environmental factors, which should be considered in the risk assessment of pharmaceuticals.

Bioavailability and toxicity of trace metals (Cd, Cr, Cu, Ni, and Zn) in sediment cores from the Shima River, South China

Five sediment cores (S1-S5) were collected from the Shima River to determine the bioavailability of trace metals (Cd, Cr, Cu, Ni, and Zn) using the modified European Community Bureau of Reference (BCR) procedure. The toxic effects of polluted sediment were assessed using the LUMISTox^® bioassay with Vibrio fischeri and chemical models such as the toxicity unit (TU) of each metal, sum of all TUs (∑TU), and toxic risk index (TRI). The results showed that Cd, Ni, and Zn were present mainly in the acid-soluble and residual fractions, and the residual fraction of Cr accounted for the majority of the metal content (44%), while Cu was present mainly in the reducible and residual fractions. Cd had a mean enrichment factor (EF) of 15.1 and was considered to be severely enriched, while there was a minor enrichment of Cr and moderately severe enrichment of Zn, Cu, and Ni. From the LUMISTox^® bioassay, an acute TU (TUa) value exceeding 0.4 was found at the upper and middle reach sites and was considered to represent slightly acute toxicity, whereas little acute toxicity was found at the lower reach site. The acid-soluble fraction of trace metals was the geochemical fraction mainly responsible for the acute toxicity of the sediment, and acid-soluble Zn and Ni were identified as important contributors to sediment toxicity.

Mutagenic and genotoxic effects and metal contaminations in fish of the Amambai River, Upper Paraná River, Brazil

The present study evaluated mutagenic and genotoxic effects and metal accumulation in the liver and musculature of Pterygoplichthys ambrosetti and Prochilodus lineatus in the Amambai River, a tributary of the Upper Paraná River in Brazil. We also evaluated the potential for these fish species as environmental bioindicators and performed risk assessment for conservation purposes. We found that P. ambrosetti had a higher frequency of micronuclei compared to P. lineatus (p < 0.0001). There were no significant differences between species in other erythrocyte nuclear abnormalities (ENA) (p > 0.05). For both species, the liver contained a higher concentration of metals (Cd, Pb, Cr, Cu, Fe, Zn, and Ni) than the musculature did (p < 0.0001). Of the two species, P. ambrosetti was more suitable to evaluate mutagenic and genotoxic effects and metal accumulation in the liver and musculature, likely due to its resident behavior; hence, we highlight the potential of this species for use as an environmental bioindicator. The concentrations of non-essential metals observed in the fish confirm conditions of environmental stress in the Amambai River, possibly related to the discharge of pollutants and exacerbated by lack of native vegetation cover along the watercourse.

Tracing Cr, Pb, Fe and Mn occurrence in the Bahía Blanca estuary through commercial fish species

Over the last decades the anthropogenic contamination impact has substantially increased in the Bahía Blanca estuarine area, and scarce information exists regarding metals in the biotic compartment of this estuary. Thus, fish tissues were used to evaluate metal accumulation within this aquatic environment. The study focused on the determination of Cr, Pb, Fe and Mn in the gills, liver and muscle tissues of six commercial fish species (Brevoortia aurea, Odontesthes argentinensis, Micropogonias furnieri, Cynoscion guatucupa, Mustelus schmitti and Paralichthys orbignyanus). From the results it can be summarized that C. guatucupa tends to accumulate higher metal levels in the liver tissues, mostly Cr and Fe, than the other studied species. O. argentinensis and P. orbignyanus, both permanent inhabitants of the BBE, achieved the highest metal values in the gill tissues, mostly in comparison to M. schmitti. The gill tissues were found to be the main organ of Mn and Ni accumulation for most species, whereas in general, minimum concentrations were found for all the analyzed metals in the muscle tissues. Nevertheless, and according to the guidelines, all fish species showed at least one sample with concentrations of Mn and/or Cr above the permissible levels for human consumption. Finally, it was highlighted the usefulness of selecting these fish species as bioindicators of metal pollution, since they are either permanent inhabitants of the estuary or, according to the sizes under analyses, spend much of their time in this coastal waters.

Enantioselective Bioaccumulation, Tissue Distribution, and Toxic Effects of Myclobutanil Enantiomers in Pelophylax nigromaculatus Tadpole

Research on the enantioselective behavior of chiral pesticides on amphibians has received growing attention, because amphibians are experiencing a population decline and amphibian metamorphosis shares many similarities with human fetal development. In this study, the enantioselective behavior of myclobutanil on Pelophylax nigromaculatus tadpole was studied. The antioxidant enzyme (SOD, GST) activities and malondialdehyde (MDA) content were investigated to assess the different toxic effects when tadpoles were exposed to myclobutanil enantiomers for 96 h. In the chronic exposure experiment, the bioaccumulation concentration of (-)-myclobutanil in tadpoles is significantly higher than that of (+)-myclobutanil, and the concentration of myclobutanil in tadpole intestine and liver was higher compared with other tissues. During the elimination experiment, about 95% of myclobutanil in tadpoles was eliminated within only 24 h. On the basis of these data, the enantiomeric differences should be taken into consideration in the risk assessment of myclobutanil.

A protocol for identifying suitable biomarkers to assess fish health: A systematic review

Background

Biomarkers have been used extensively to provide the connection between external levels of contaminant exposure, internal levels of tissue contamination, and early adverse effects in organisms.

Objectives

To present a three-step protocol for identifying suitable biomarkers to assess fish health in coastal and marine ecosystems, using Gladstone Harbour (Australia) as a case study.

Methods

Prior to applying our protocol, clear working definitions for biomarkers were developed to ensure consistency with the global literature on fish health assessment. First, contaminants of concern were identified based on the presence of point and diffuse sources of pollution and available monitoring data for the ecosystem of interest. Second, suitable fish species were identified using fisheries dependent and independent data, and prioritised based on potential pathways of exposure to the contaminants of concern. Finally, a systematic and critical literature review was conducted on the use of biomarkers to assess the health of fish exposed to the contaminants of concern.

Results/Discussion

We present clear working definitions for bioaccumulation markers, biomarkers of exposure, biomarkers of effect and biomarkers of susceptibility. Based on emission and concentration information, seven metals were identified as contaminants of concern for Gladstone Harbour. Twenty out of 232 fish species were abundant enough to be potentially suitable for biomarker studies; five of these were prioritised based on potential pathways of exposure and susceptibility to metals. The literature search on biomarkers yielded 5,035 articles, of which 151met the inclusion criteria. Based on our review, the most suitable biomarkers include bioaccumulation markers, biomarkers of exposure (CYP1A, EROD, SOD, LPOX, HSP, MT, DNA strand breaks, micronuclei, apoptosis), and biomarkers of effect (histopathology, TAG:ST).

Conclusion

Our protocol outlines a clear pathway to identify suitable biomarkers to assess fish health in coastal and marine ecosystems, which can be applied to biomarker studies in aquatic ecosystems around the world.

Bioaccumulation and trophic transfer of pharmaceuticals in food webs from a large freshwater lake

Pharmaceuticals are increasingly detected in environmental matrices, but information on their trophic transfer in aquatic food webs is insufficient. This study investigated the bioaccumulation and trophic transfer of 23 pharmaceuticals in Taihu Lake, China. Pharmaceutical concentrations were analyzed in surface water, sediments and 14 aquatic species, including plankton, invertebrates and fish collected from the lake. The median concentrations of the detected pharmaceuticals ranged from not detected (ND) to 49 ng/L in water, ND to 49 ng/g dry weight (dw) in sediments, and from ND to 130 ng/g dw in biota. Higher concentrations of pharmaceuticals were found in zoobenthos relative to plankton, shrimp and fish muscle. In fish tissues, the observed pharmaceutical contents in the liver and brain were generally higher than those in the gills and muscle. Both bioaccumulation factors (median BAFs: 19-2008 L/kg) and biota-sediment accumulation factors (median BSAFs: 0.0010-0.037) indicated a low bioaccumulation potential for the target pharmaceuticals. For eight of the most frequently detected pharmaceuticals in food webs, the trophic magnification factors (TMFs) were analyzed from two different regions of Taihu Lake. The TMFs for roxithromycin, propranolol, diclofenac, ibuprofen, ofloxacin, norfloxacin, ciprofloxacin and tetracycline in the two food webs ranged from 0.28 to 1.25, suggesting that none of these pharmaceuticals experienced trophic magnification. In addition, the pharmaceutical TMFs did not differ significantly between the two regions in Taihu Lake.

A comparison of metal concentrations in the tissues of yellow American eel (Anguilla rostrata) and European eel (Anguilla anguilla)

Historically abundant and widespread, populations of Atlantic eels have suffered a sharp decline in recent decades, in the ranges 40-80% and 90-99% for American and European eels, respectively. As a result, American eels are now classified as threatened, whereas European eels are considered to be in critical danger of extinction. Several causes have been identified as likely contributors of this decline, including overfishing, obstacles to migration (hydroelectric dams), climate change and habitat contamination. In the context of a larger project investigating the role of organic and inorganic contaminants in this decline, in this study, we measured the liver, kidney and muscle concentrations of essential (Cu, Se and Zn) and non-essential (Ag, As, Cd, Cr, Hg, Ni and Pb) metals in eels sampled at four sites in the South-West of France and four sites in Eastern Canada varying in contamination. Tissue concentrations of Cd, Hg and Se increased with fish size and age. Tissue metal concentrations generally reflected the contamination of their sampling sites. This was the case for Ag, As, Cd, Cu, Hg, Pb and Se. Comparison of tissue concentrations of these metals with the toxicological literature suggests that all of them except As could pose a risk to the health of eels from the most contaminated sites. In particular, European eels may be particularly at risk of Cd and Pb toxicity. Globally, our study suggests that a substantial accumulation of inorganic contaminants in the tissues of both eel species at sites contaminated by historical anthropogenic inputs may play a role in their decline.

Screening beneficial rhizobacteria from Spartina maritima for phytoremediation of metal polluted salt marshes: comparison of gram-positive and gram-negative strains

The aim of our work was the isolation and characterization of bacteria from the rhizosphere of Spartina maritima in the metal contaminated Odiel estuary (Huelva, SW Spain). From 25 strains, 84 % were identified as gram-positive, particularly Staphylococcus and Bacillus. Gram-negative bacteria were represented by Pantoea and Salmonella. Salt and heavy metal tolerance, metal bioabsorption, plant growth promoting (PGP) properties, and biofilm formation were investigated in the bacterial collection. Despite the higher abundance of gram-positive bacteria, gram-negative isolates displayed higher tolerance toward metal(loid)s (As, Cu, Zn, and Pb) and greater metal biosorption, as deduced from ICP-OES and SEM-EDX analyses. Besides, they exhibited better PGP properties, which were retained in the presence of metals and the ability to form biofilms. Gram-negative strains Pantoea agglomerans RSO6 and RSO7, together with gram-positive Bacillus aryabhattai RSO25, were selected for a bacterial consortium aimed to inoculate S. maritima plants in metal polluted estuaries for phytoremediation purposes.

Blue sharks (Prionace glauca) as bioindicators of pollution and health in the Atlantic Ocean: Contamination levels and biochemical stress responses

Marine ecosystems are constantly being threatened by contaminants produced by human activities. There is an urge to better understand their impacts on marine organisms and develop reliable tools for biomonitoring studies, while also assessing their potential impacts on human health. Given their position on top of food webs, sharks are particularly susceptible to bioaccumulation, making them potential sentinel species of marine contamination. The main objective of this study was to find suitable biomarkers for future marine pollution biomonitoring studies by correlating biochemical responses with tissue contaminant body burden in blue sharks (Prionace glauca), a species heavily caught and consumed by humans, while also addressing their general health. The chemical contaminants analysed comprised different persistent organic pollutants (POPs) families from polychlorinated compounds to brominated flame retardants (BFRs) and perfluorinated compounds (PFCs) and different trace and heavy metals. Concentrations of some contaminants in sharks' tissues were found to be above the legally allowed limits for human consumption. A canonical correspondence analysis (CCA) was performed and some strong associations were found between biochemical responses and contaminants' accumulation levels. DNA damage and lipid peroxidation levels, as well as the inhibition of the antioxidant enzyme glutathione peroxidase, were the main effects and consequences of contamination. The impact of contamination on these vital macromolecules underlines the suboptimal conditions of the sampled P. glauca, which can ultimately lead to the degradation of core ecological aspects, such as swimming, feeding, and reproduction. It can be concluded that P. glauca demonstrates great potential to be used as environmental sentinel and suitable biomarker candidates were identified in this work. Moreover, this study also highlights the risks that the consumption of blue shark derived products can pose to human health, which is of upmost interest as the sampled organisms were still juveniles and already presented values above regulatory limits.

Impact of metal pollution, food availability, and excessive fishing on Rhabdosargus haffara stock (family: Sparidae) in Timsah lake

The lakes' fisheries play an important role in Egyptian economy. In 1980s, they provided more than 50 % of harvested fish in Egypt but now their contribution to the Egypt fish production decreased to only 12.5 % in 2012. Lake Timsah, one of the Suez Canal lakes, faced many challenges that lead to serious changes in its water and fish quality, fish production, as well as the catch composition. The present work investigated the impact of pollution, food availability, and excessive fishing mortality on the haffara production in lake Timsah. The distribution of four heavy metals (Pb, Zn, Ni, and Fe) was detected seasonally in water and in muscles, gills, and livers of Rhabdosargus haffara, during 2012 through 2013. Fe and Zn were presented by high values in liver, while Pb and Ni in gills. Generally, the lowest concentrations of all metals were found in muscles. The recorded crustacean organisms (the main food of haffara) decreased from 12 species and 32,079 organisms⁄m(2) in 2012 to only 7 species and 7290 organisms⁄m(2) in 2013 while the amphipods completely disappeared. This serious change was due to the severe pollution in the lake. A logistic surplus production model was fitted to the catch per unit effort indices, to estimate the maximum sustainable yield and the optimum level of fishing effort. The results revealed that haffara stock at lake Timsah is overfished, and the estimated precautionary target reference points advised the reduction of fishing effort by about 30-50 %.